The present invention relates to apparatus for setting a horizontal plane, using a conventional level, particularly a spirit level having a housing, or if appropriate, a laser spirit level.
Leveling plates have been used for many years for leveling theodolites and other optical measuring instruments. They usually include upper and lower plates, which can be adjusted with respect to each other in two planes with the aid of adjustment screws, and leveling means in the form of a spirit level with which the horizontal alignment can be monitored. A leveling plate includes a further device, for example a threaded connection, for fastening the plate on a stand as well as securing means for fastening the actual measuring instrument to the plate.
Recently, there has been increasing use of so-called laser spirit levels. This is an optical measuring instrument with two leveling means oriented at right angles with respect to one another, and whose form and structure corresponds to that of a conventional spirit level. A laser and suitable optics are accommodated in the housing. The laser beam is adjusted to be exactly parallel to the measuring base of the spirit level body.
For fastening spirit levels, irrespective of whether they have a laser integrated in them, conventional leveling plates have special generally U-shaped clamping devices. The bearing surfaces of the devices have to be aligned with a high degree of precision so that they are at right angles with respect to the pivot axis of the leveling plate. This requires high machining costs. Fastening the spirit level in the clamping device also requires great accuracy by the user. Finally, conventional leveling plates are also equipped with complex mountings, in order that the optical measuring instrument might be adjusted, and particularly pivoted, precisely. These are costly because they should be free of play. Often, however, these mountings are not free of play, or over time become no longer free of play. Thus they have to be regularly readjusted. Moisture and dirt may also cause disruptions.